Sunvisors for vehicles which have panels or visors slidably or telescopically mounted on support arms are known. An early example of such a sunvisor is found in Schoenheit, U.S. Pat. No. 2,201,377. This particular sunvisor uses a simply supported leaf spring on a panel to engage a support arm thus positioning the panel relative to the support arm. When the leaf spring engages an intermediate flat on the support arm, the panel is easily slid longitudinally along the support arm. However, when the panel is rotated such that the leaf spring engages a cylindrical rather than flat portion of the support arm, sufficient frictional engagement is created between the leaf spring and the support arm to prevent sliding movement therebetween and consequently between the panel and the support arm.
Another example is found in Clark, U.S. Pat. No. 4,925,233, which requires a pair of longitudinally spaced apart pivot blocks which interact with a support arm and a pair of guide rods. The pivot blocks have apertures therein which frictionally engage the guide rods to limit the sliding of a panel upon the support arm.
However, both sunvisors are relatively complicated and expensive to manufacture. Further, both sunvisors fail to provide provisions for stably biasing the sunvisor to both stowed and deployed positions using a relative simply design.